Low temperature coefficient of resistivity cermet resistors

ABSTRACT

Cermet resistors based on ruthenium dioxide and in some instances iridium dioxide have been found to have unusually low Temperature Coefficients of Resistivity (TCR) when a particular glass frit and a vanadium oxide additive are utilized. These unique resistors exhibit TCR&#39;&#39;s of less than + OR - 25 ppm/*C over -55 to +150*C with the extremes of the TCR varying less than 20 ppm. The vanadium, iridium and ruthenium oxides can be used as such or derived from metal resinates.

United States Patent" 1 Pukaite [451 Aug. 12, 1975 LOW TEMPERATURE COEFFICIENT OF RESISTIVITY CERMET RESISTORS [75] Inventor: Clifford Joseph Pukaite, Mequon,

Wis.

[73] Assignee: Globe-Union Inc., Milwaukee, Wis.

[22] Filed: May 11, 1973 [21] Appl. No.: 359,244

52 U.S. Cl 252/518; 252/521 [51] Int. Cl. ..H01B H06 [58] Field of Search 252/518 [56] References Cited UNITED STATES PATENTS 3,304,199 2/1967 Faber, Sr. et a1. 252/518 X 3,440,182 4/1969 Hoffman 252/514 3,679,607 7/1972 Angus et a1 252/518 Primary Examiner-Benjamin R. Padgett Assistant Examiner-+15. Suzanne Parr Attorney, Agent, or Fi'rrri.-James L. Kirschnik; John Phillip Ryan to +150C with the extremes of the TCR varying less than 20 ppm. The vanadium, iridium and ruthenium oxides can be used as such or derived from metal resinates.

14 Claims, .2 Drawing Figures LOW TEMPERATURE COEFFICIENT or REsIsTiv'rrv CERMET RESISTORS' BACKGROUND OF THE INVENTlQN if i stability of cermet resistors is not completely under-. stood. It has been observed that variousv semiconductv ing oxides exert an influence on thetemp'er ature response of resistivity of cermet resistors so as to make them more thermally stable. Prior to this invention, only resistors described in the electronics industry as thin film resistors have displayed low TCRs. ln US. Pat. Nos. 2,950,995; 2,950,996 and 3,516,949 vanadium oxide is used in conjunction with noble metal metallizing compositions in relatively small amounts to prevent agglomeration of the metal particles and to improve the solderability, conductivity and/or adhesion properties of the metallizing materials. The same indication of improvement in solderability for these compositions by adding vanadium pentoxide is also indicated in US. Pat. No. 3,440,182.

In US. Pat. No. 3,553,109 vanadium pentoxide is uti lized to control TCR in a resistor composition of the bismuth ruthenate type which utilizes a glass frit binder consisting of 80% lead oxide, 10 si1icon oxide and 10% boron oxide.'Aglasswas prepared from the teachings of this particular patentand combined with a conductive phase used to fabricate the-resistors of this invention composedfi'of. ruthenium dioxide; vanadium pentoxide, and aluminum trioxide as set forth in Example l 1. It had a sheet resistiyity of .5.49K ohm/sq./mil. and a TCR of H'IO'i l ;.ppr n[?C whenaneasured between +25 and 5 5C ar id. ai l-2j0 t 1.0 ppm/fC when measured between +25 ,an.d, +,15 0C. These results clearly indicate that a low TCR cannot be obtained with ruthenium dioxide and vanadium pentoxide which are the preferred materials of this invention when utilized with the glass described in thisparticular' patent. An attempt wasalso made to prepare a low TCR resistor material utilizing apurchased t glass con taining l 1% calcium oxide, 441% lead oxide, 4.0% aluminum trioxide, 5.5% boron trioxide and 354% silicon dioxide. This glass material was combined with a conductive material composed of ruthenium dioxide in an amount of 5.34 w eight percent preparedfrom ruthenium resinate containing 5.26 weight pereentruthenium dioxide, iridium dioxide in an amount of 7v.2 weight percent pre pared from iridium resinate containing 6.99 weight percent iridium dioxide, 2.95 weightpercent bismuth trioxide, 4.18 weight percentvanadiurn pentoxide and the previously described glass in the; ,amount .of 80.41 weight percent. The resistivelmaterial prepared, had a sheet resistivityof 24,000 ohms/sqjmil. and a TCRvOf l 60 i 10 ppm/C whe n measured between -1'- 25?C"and -55C and a 505: 10 ppm/9C when measured between +2 5?C and +150C-Iwhich' 'is considered poorer than when using thcmaterials of this invention.

It is an object of the present invention-to provide a novel resistorcomposition"whereinthe temperature coefficient of resistivity is held within a narrow plus and 2 minus range over-a broad temperature range. It is another object of this invention to provide a lowtcmperature coefficient of resistivity for a cermet material wherein a vanadium oxide is combined with ruthenium andiridium-dioxides in designated quantities. It is still another object of this invention to provide a cermet type resistorwith a low TCR which is accomplished by employing vanadium oxides with a particular glass frit. It is yet another object of this invention to provide a low TCR-cermet resistor which can be produced by currentzmethods of manufacture and can employ either oxide or metallic resinate precursor materials for both the noble metal oxides and the vanadium oxide.

SUMMARY OF THE INVENTION The foregoing objects are accomplished and the shortcomingsof the prior art are overcome by thepresent resistor composition wherein a conductive phase composed of ruthenium dioxide and, preferably, in addition iridium dioxide, is combined with a vanadium oxide in designated quantities and with a glass phase composed of a glass frit of a particular composition. These materials are fired together to result in the "unique resistor composition having unexpected low TCRs over a broad temperature range. Alternatively, bismuth trioxide can be utilized in the resistive material composition. The ruthenium, iridium and vanadium oxides can be supplied in their oxide form or in the form of resinate precursor materials combined with the particular glass frit.

BRIEF DESCRIPTION OF DRAWING ing these same critical characteristics but for the resistor material prepared from oxides as described .in Examples l 1, 14 and 15 with the data plotted for these particular materials.

DESCRIPTION OF THE RESINATE EMBODIMENT The cermet resistor composition of this invention can be prepared either by utilizing the ruthenium and iridfium dioxides in a resinate form for ultimate conversion to the dioxidefor can be prepared by utilizing the ruthenium and/or iridium dioxides themselves as starting materials. A description of'the cermet resistor composition' as prepared from the resinates of ruthenium and iridium will first be" given. The particular resinates of ruthenium and iridium employed in the Examples of Table III andin" Examples 20, 21 and 22 are designated A-l 124 arid A-l 123, respectively, by the supplier, Engelhard Industries, Inc., 'I-lanovia Liquid Gold Division of East Newark; N. J. They are resinate solutions containing4l0% ruthenium or'5.26% ruthenium dioxide and 6.0% iridium or 6.99% iridium dioxide, respectively. The range of starting materials for the resinateprepared compositions and for the glass are described in the following Tables I and II.

TABLE 1 Composition Range of Resistive Material (Conductive Phase) 6. Screen print onto a ceramic insulating substrate by methods common to the thick film electronic art. An example of applicable substrate material is CRL 95 alumina. (Centralab Division of Globe-Union lnc.)

Constituents y Weigh! 2 6x 9" 5 7. Fire at 850C to 950C in belt kiln using a 0.5 to

3 hour firing cycle. Ruthenium Resinate 20.00 to 85.00 1.00 to 30.00 Table 111 illustrates the compositions and test results Iridium Resinate 5.00 to 45.00 1.00 to 15.00 g I I Bismuth Tfioxidc 000 to 225 000 m mm) for the novel resistor material prepared in accordance vanadium pemoxidc 0,50 w 25 00 to mm with this invention and employing ruthenium and irtd- Glass to 40-00 59-00 ium resinates as starting materials.

TABLE 111 Raw Material Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Ex. 7 Ex. 8 Ex. 9 Ex. 10

Ru Resinate wt. 22.16 9.30 4.76 3.55 3.52 24.32 10.38 5.36 2.12 1.79 (5.26% RuO- lr Resinate wt. 70* 3.32 13.04 6.69 4.97 4.93 3.46 13.81 7.12 6.23 2.36 (6.99% lrO Bi Q, \vt. 3.30 3.04 2.98 4.58 4.55 2.93 2.99 2.95 1.89 0.14 V 0 wt. "/2 5.75 6.48 4.23 5.00 5.57 5.82 5.81 4.17 1.34 0.46 Glass FB-l99N** wt. 71 65.72 68.14 81.33 81.89 81.41 63.46 67.01 80.39 88.41 95.25 Average Sheet*** Resistivity 200 3 10 l ,300 2,600 3,070 100 300 1,500 3.000 10.000

ohm/sqJmil. Average TCR ppm/C**** 55C to C 28 8 +3 2 23 l5 l3 5 +1 l4 25C to 150C +4 l5 +15 6 21 +16 +5 +10 +14 +56 Based on oxide composition "Ferro Corporation: 44.9% wt. PhO; 20.1% wt. 8,-0. 35.0% wt. SiO ***All figures for Average Sheet Resistivity are in round numbers ""TCR measured to i a TABLE As is seen in Table 111, and particularly Example 10, the best results are obtained utilizing the resinate starting Composition Range of Glass Matrix materials at lower resistive values.

(Glass Phase) Constituent By weight By welghl Preferred Pbo 450 40 Examples 1 l-l8 in Table V illustrate the utilization B 0 15.0to25.0 17.0 to 21.0 f th h I i l d sioz 300 m 400 33.0 m 370 o ru emum on e as t e start ng materla com me CaO 0 to 2.0 1.810 with a glass frit generally described in Table 11. For a 0 w m series of resistive materials, using oxides as starting ma- In the following Examples ll0, 20, 21 and -22, deriving the oxides from resinate precursors, the following procedures which are standard in this art are employed in all instances:

RESlNATE METHOD 1. Weigh constituents in desired proportions.

2. Burn off organic portions of resinate solution at 300C to 480C in the presence of the glass frit of median particle size of less than 20 microns.

3. Calcine inorganic residue for 30 to 90 minutes at 400 to 600C in air.

4. Reduce the particle size of the residue to less than 20 microns, preferably to a median particle size of 5 i 2 microns by such means as ball milling with alumina grinding media.

5. Mix the resulting powder with a suitable vehicle to a paste of desired consistency. The vehicle may consist of any number of high boiling point organic liquids such as l-ethyl-2-hexanol which, in combination with the resistive powder, have a viscosity suitable for screen printing, dipping, or painting onto a substrate.

:tei'ials, the compositions described in the following Table IV are suitable:

TABLE IV Composition Range of Resistive Material (Conductive Phase) Constituent By Weight By Weight Preferred RuO, 1.00 to 30.00 2.00 to 25.00 lrO 1.00 to 15.00 3.00 to 14.00 Bi Q, 0.00 to 10.00 0.00 to 5.00 V 0 1.00 to 10.00 1.00 to 8.00 A1 0 0.00 to 10.00 0.(X) to 7.00 G1ass* 50.00 to 98.00 63.00 to 95.00

Same compostion as in 'lnhle II OXIDE METHOD 1. Weight constituents in desired proportions.

The following Example 20 illustrates the utilization of vanadium pentoxide predissolved in the glass desig- 5 nated FB-l99N to the extent of 6.48% b wei ht. 2. MIX constituents together 1n a ball mill with acey g tone to form a slurry and ball mill with a grinding me- Example 20 dium alumina for 0.1 to 8.0 hours.

3. Dry mixture at 70C. 4. Mix with a vehicle such as l-ethyl-2-hexano1 to m lngredems %By wcightoxide form P Ruthenium Resinate 10.37

5. Mill the resulting paint in a three roll mill for 0.1 Qz) to 2 hours to assure dispersion and adjust consistency figg 2 for screen printing by adding solvent. 2.99

6. Screen onto a ceramic insulating substrate. Glass 7 I 850C 950C 4 b l FB 199N/v.,o

ire at to in a e t type 1ln in a 0.5 (P349910. as indicated to 3 hour firlng cycle. in Tables 111 and V) j 72.85

TABLE V Raw Material Ex. 11 Ex. 12 Ex. 13 Ex. 14 Ex. 15 'Ext l6 Ex. 17 Ex. 18

RuO 'wt. 7c 5.67 5.95 4.73 3.90 4.60 3.75 5.78 5.78 M.B. M.B

Type A* Type P" 1:0 wt. '7 v. ,o wt. /1 2.83 2.77 3.15 1.90 1.90 1.50 1.73 1.73 A1 O wt. 0.75 1.41 6.90 7.00 a. Glass FB-199N*** wt. /1 90.73 90.26 85.22 94.1 86.50 i94.75 92.49 92.49 Average Sheer v Resistivity**** 6180 8600 27,900 53,200 1 12,900 449,100 400,000 30,000

ohm/sqJmil. Average TCR ppmlC***** 55Cm 25C 0 +10 +16 -23 8 14 6 25C to 150C +4 +10 18 +14 +24 +12 +23 M13; Mutlhey Bishop Type A "MB; MutLhey Bishop Type P "Sume as Table ll ""Note: All figures for Average Sheet Resistivity are in round numbers "'"TCR's measured to z 3 ppm/"C Example 19 Ingredients "/1 By Weight Ruthenium Hydrate 5.78 (55% RuO V. ,O:, 1.73 Glass FB-199N (As indicated in Tables III and V) 92.49

This material is processed in the same method as indicated for the oxide starting materials under the head- 60 ing Oxide Method."

Results:

Sheet Resistivity: 20.000 ohms/sq./mi1. TCR ppm/C:

S5C to 25C 25C to 150C As indicated in this Example 19, when the ruthenium oxide is added in the form of the hydrate the TCR is not as low as when the starting material is the oxide or the resinate.

These materials are processed by the method indicated above under the heading Resinate Method."

Results: Sheet Resistivity: approximately 500 ohms/sqJmil. TCR ppm/C: 55C to 25C 29 1 3 25C to 150C 27 i 3 In all of the previous Examples, the vanadium oxide has been introducedpreferably as vanadium pentoxide.

It should be understood that other oxides of vanadium such as vanadium t'rioxicle can likewise be employed. Additionally, the vanadium oxide can be introduced through a vanadiuni'resirrate precursor material. Examples 21 and 22 following illustrate these.

Example 21 Ingredients 7( By Weight Oxide Ruthenium Resinate 10.48 (5.26% RuO Iridium Resinate 13.93 (6.99% lrO. V 0 4.84 Bi Q, 3.02 Glass FB- 199N (As indicated in Tables Ill and V) 67.72

These materials are processed by the method indicated above under the heading Resinate Method."

7 Results:

Shcct Resistivity: approximately 330 ohms/sq./mil. TCR ppm/C:

55C to 25C +13 1 3 25C to 150C +19 3 The following Example 22 indicates utilization of vanadium oxide introduced as vanadium resinate.

The above materials are processed by the method indicated above under the heading Resinate Method.

Example 22 Results: Sheet Resistivity: 280 ohmslsqjmil. TCR ppm/"C:

55C to 25C +26 1 3 25C to 150C +21 3 As indicated above, the important conditions for achieving the low temperature coefficient of resistivity are the utilization of vanadium oxide with ruthenium dioxide, which preferably can also include iridium dioxide, in the designated amount with a particular glass composition. The vanadium oxide as well as the ruthenium and iridium dioxides can be utilized as oxides or derived from resinate precursors. While vanadium pentoxide is the preferred oxide of vanadium, other oxides such as vanadium trioxide or those oxides resulting from the pyrolysis of vanadium resinate can likewise be employed to advantage.

It will thus be seen that through the present inven- I tion, there is now provided a cermet resistor composition having a low temperature coefficient of resistivity which can be effected at the extremes and generally less than 20 ppm/C, maintained over a broad temperature range. The vanadium oxide can be utilized in various stages of oxidation and in the form of theresinate as can the ruthenium and the iridium dioxides. The materials are easily processed into resistive paints. No additional capital investment need be incurred to substitute the cermet resistor compositions of this invention for more conventional compositions, and they can be easily fabricated into thick film resistors without additional skills being required by the fabricator.

The foregoing invention can now be practiced by those skilled in the art. Such skilled persons will know that the invention is not necessarily restricted to the l'uscd to a substrate composed ofhigh temperature, electrically nonconductive material comprising: a conductive phase composed of vanadium oxide in the range from about 1.00 to about 10.00 weight'percent and ruthenium dioxide in the range of from about 1 .00 to about 30.00 weight percent, and an interdispersed glass phase in the range of about 50100 to about 98.00 weight percent, said glass phase composed of lead oxide in the range of about 35.00 to about 45.00 weight percent, boron trioxide in the range of about 15.00 to about 25.00 weight percent and silicon dioxide present in the range of about 30.00 to about 40.00 weight percent.

2. The cermet resistor composition as defined in claim 1 further including iridium dioxide present in the range of about 1.00 to about 15.00 weight percent.

3. The cermet resistor composition as defined in claim 2 wherein said ruthenium dioxide is present in the range of about 2.00 to about 25.00 weight percent, said iridium dioxide is present'in the range of about 3.00 to about 14.00 weight percent, said vanadium oxide is present in the range of about 1.00 to about 8.00 weight percent and said glass phase is present in the range of from about 63.00 to about 95.00 weight percent.

4. The cermet resistor composition as defined in claim 3 wherein said glass phase is composed of lead oxide present in the range of about 38.00 to about 45.00 weight percent, said boron trioxide is present in the range of about 17.00 to about 21.00 and said silicon dioxide is present in the range of about 33.00 to about 37.00 weight percent.

5. The cermet resistor composition as defined in claim 2 wherein said vanadium oxide is vanadium pentoxide.

6. The cermet resistor composition as defined in claim 2 wherein said composition further includes bismuth trioxide present in an amount not greater than about 10.00 weight percent.

7. The cermet resistor composition as defined in claim 2 wherein said glass phase contains calcium oxide present in an amount not greater than about 2.00 weight percent.

8. The cermet resistor composition as defined in claim 7 wherein said calcium oxide is present in the range of about 1.00 to about 2.00 weight percent.

9. The cermet resistor composition as defined in claim 2 wherein said composition includes aluminum trioxide present in an amount not greater than about 10.00 weight percent.

10. The cermet resistor composition as defined in claim 9 wherein said aluminum trioxide is present in resinate present in the range of about 20.00 to about particular embodiments herein. The scope of the inven- I tion is to be defined by the terms of the following claims as given meaning by the preceding description.

1 claim: 1. A cermet resistor composition having a low temperature coefficient of resistivity and adapted to be .00, weight percent, iridium resinate present in the range of about 5.00 to about 45.00 weight precent, vanadium oxide present in the range of about 0.50 to 2.50

weight percent and glass frit present in the range of about 5.00 to 40.00 weight percent, said glass frit comprising lead oxide present in the range of about 35.00

9 10 v to 45.00 weight percent, boron trioxide present in the including bismuth trioxide present in an amount not range of about 15.00 to about 25.00 weight percent greater than about 2.25 weight percent. and silicon oxide present in the range of about 30.00 to 14. The composition as defined in claim 11 wherein about 40.00 weight percent. said vanadium oxide is vanadium pentoxide.

13. The composition as defined in claim 11 further 5 

1. A CERMET RESISTOR COMPOSITION HAVING A LOW TEMPERATURE COEFFICIENT OF RESISTIVITY AN ADAPTED TO BE FUSED TO A SUBSTRATE COMPOSED OF HIGH TEMPERATURE, ELECTRICALLY NONCONDUCTIVE MATERIAL COMPRISING: A CONDUCTIVE PHASE COMPOSED OF VANADIUM OXIDE IN THE RANGE FROM ABOUT 1.00 TO ABOUT 10.00 WEIGHT PERCENT AND RUTHENIUM DIOXIDE IN THE RANGE OF FROM ABOUT 1.00 TO ABOUT 30.00 WEIGHT PERCENT, AND AN INTERDISPERSED GLASS PHASE IN THE RANGE OF ABOUT 50.00 TO ABOUT 98.00 WEIGHT PERCENT, SAID GLASS PHASE COMPOSED OF LEAD OXIDE IN THE RANGE OF ABOUT 35.00 TO ABOUT 45.00 WEIGHT PERCENT, BORON TRIOXIDE IN THE RANGE OF ABOUT 15.00 TO ABOUT 25.00 WEIGHT PERCENT AND SILICON DIOXIDE PRESENT IN THE RANGE OF ABOUT 30.00 TO ABOUT 40.00 WEIGHT PERCENT.
 2. The cermet resistor composition as defined in claim 1 further including iridium dioxide present in the range of about 1.00 to about 15.00 weight percent.
 3. The cermet resistor composition as defined in claim 2 wherein said ruthenium dioxide is present in the range of about 2.00 to about 25.00 weight percent, said iridium dioxide is present in the range of about 3.00 to about 14.00 weight percent, said vanadium oxide is present in the range of about 1.00 to about 8.00 weight percent and said glass phase is present in the range of from about 63.00 to about 95.00 weight percent.
 4. The cermet resistor composition as defined in claim 3 wherein said glass phase is composed of lead oxide present in the range of about 38.00 to about 45.00 weight percent, said boron trioxide is present in the range of about 17.00 to about 21.00 and said silicon dioxide is present in the range of about 33.00 to about 37.00 weight percent.
 5. The cermet resistor composition as defined in claim 2 wherein said vanadium oxide is vanadium pentoxide.
 6. The cermet resistor composition as defined in claim 2 wherein said composition further includes bismuth trioxide present in an amount noT greater than about 10.00 weight percent.
 7. The cermet resistor composition as defined in claim 2 wherein said glass phase contains calcium oxide present in an amount not greater than about 2.00 weight percent.
 8. The cermet resistor composition as defined in claim 7 wherein said calcium oxide is present in the range of about 1.00 to about 2.00 weight percent.
 9. The cermet resistor composition as defined in claim 2 wherein said composition includes aluminum trioxide present in an amount not greater than about 10.00 weight percent.
 10. The cermet resistor composition as defined in claim 9 wherein said aluminum trioxide is present in the range of about 1.00 to about 7.00 weight percent.
 11. The cermet resistor composition as defined in claim 1 wherein said glass phase contains calcium oxide present in the range of about 1.00 to about 2.00 weight percent and aluminum trioxide present in the range of about 1.00 to about 2.00 weight percent.
 12. A starting material composition for manufacturing the composition of claim 1 comprising ruthenium resinate present in the range of about 20.00 to about 85.00 weight percent, iridium resinate present in the range of about 5.00 to about 45.00 weight precent, vanadium oxide present in the range of about 0.50 to 2.50 weight percent and glass frit present in the range of about 5.00 to 40.00 weight percent, said glass frit comprising lead oxide present in the range of about 35.00 to 45.00 weight percent, boron trioxide present in the range of about 15.00 to about 25.00 weight percent and silicon oxide present in the range of about 30.00 to about 40.00 weight percent.
 13. The composition as defined in claim 11 further including bismuth trioxide present in an amount not greater than about 2.25 weight percent.
 14. The composition as defined in claim 11 wherein said vanadium oxide is vanadium pentoxide. 